This invention relates generally to covers for foam parts of vehicle seat assemblies, such as the seat members and headrests, and more particularly to such foam parts which are improved from the standpoints of comfort and appearance by virtue of the use of the seam stabilizers of this invention in the covers for these parts.
It is a desirable objective in seating of all types, particularly vehicle seating, to provide seat components with covering materials which conform tightly to the surface of the foam pads. Such seat members are desirably formed with an interior load support section bounded by peripheral sections that function as bolsters to impart a feeling of stability and comfort to the occupant of the seat. The interior sections should further include a contoured surface to enhance the seat cushion's appearance and occupant's comfort. In order to accomplish this, the present invention utilizes separate covering members to cover the interior section and the peripheral sections of the seat member. The separate covering members are secured in place by the attachment of these members to a tear away welt, or trim strip, which is integrated into a seam at the juncture of the sections, thereby stabilizing the seam and preventing wrinkling of the cover during the pour-in-place molding process of the foam pad.
Tear away welts have previously been used in the manufacture of vehicle seats, as shown by U.S. Pat. No. 4,765,045, assigned to the assignee of this application. However, the welt shown in the patent is for seam locating purposes, not seam stabilizing.
The above mentioned patent teaches the use of the welt to position the covering material on a mold and subsequently on a pre-shaped pad. In the present invention, the welt is not secured to the mold and a pre-shaped foam pad is not required. Rather, a pour-in-place process is used to form the foam pad. There are several benefits from using the pour-in-place process to mold the foam pad instead of using a pre-shaped pad. For example, the overall production cost is lower since the step of attaching the foam pad to the cover is eliminated. Additionally, the difficulties associated with aligning a pre-shaped pad with a shaped cover are nonexistent in the pour-in-place process, thereby resulting in a better fitting cover and a faster production process.
The tear away welt of this invention is preferably molded of bendable plastic material, however, other materials providing sufficient rigidity may also be used. Initially, the welt is sewn into the covering members at their junctures, so as to stabilize the resulting seams and insure that the seam will maintain the desired shapes. A first mold member supports the covering members, and the welt, prior to molding of the foam pad. A second mold member is then positioned above the first mold member and a liquid foam material is injected into the mold cavity onto the cover members to form the foam pad to the cover assembly. The tear away welt provides accurate location of the covering members in the mold during the injection of the liquid foam material and also prevents the seam from moving and being out of alignment.
The above mentioned welt has an annular body, positioned outside the seat component during assembly, and a notched tab portion, remaining within the seated component after assembly. At the juncture of the notched tab portion with the annular body, the welt is tapered to a reduced thickness to facilitate sewing and tearing.
Once the foam pad has been poured and formed within the mold, the covering members become adhered to the foam pad. The covering members and foam pad are then removed from the mold and the annular body portion of the tear away welt strip may be removed, if desired, by tearing it away from the notched tab portion. The result is a vehicle seat component in which the covering members are tightly adhered to the foam pad and conformed to the surface irregularities and designs of the foam pad. If desired, the interior and peripheral covering members can be formed of contrasting materials since different covering members are used in covering foam parts with this invention.
The result is an apparatus and a process that is improved from the standpoints of reliability in quality assurance and a seat product that is improved from the standpoints of appearance and comfort.